Why when I want to receive all message id from FireBase it gives me some left id?

Question

Android

Why when I want to get all message id from FireBase it gives me some left id? This is how I get message id from chat

String smsUser = myRef.child("Messages").child("Sms").push().getKey();
holder.message.setText(smsUser);

The result, of course, looks like an id, but these are absolutely not the id in which the message and the information I need are stored.